The present invention relates to a detector system, and in particular a detector system for a diagnostic imaging device, such as an x-ray CT scanning device.
A conventional x-ray CT scanning device is a large stationary device having a fixed bore, and is typically located in a dedicated x-ray room, such as in the radiology department of a hospital. In a typical device, an x-ray source and a detector system are mounted within a gantry defining an imaging bore, and rotate about an object being imaged. As the x-ray source and detector system rotate, the source projects a fan- or cone-shaped beam through the object being imaged, such as a patient, and the beam is attenuated by the object before impinging on the detector system. The detector system generally comprises an array of detector elements, where each element generates an electrical signal that represents the amount of attenuated beam radiation received at a particular detector location. The measurements from all detectors in the array together form a transmission profile that can be used to reconstruct images of the object, including three-dimensional tomographic images.
As the complexity and sophistication of diagnostic imaging systems continues to increase over time, the power output from the various components of the imaging system is also increasing. These imaging systems typically generate large amount of heat during normal operation. This can be problematic, since a number of components typically found in such imaging systems, including the detector system, are highly-temperature dependent. Thus, many imaging systems include cooling systems to help manage heat flow within the device. In commonly-owned U.S. application Ser. No. 13/025,573, filed Feb. 11, 2011, for example, an internal airflow cooling system is described for cooling the internal components of a mobile diagnostic imaging system.
Within the imaging system, the detector system presents unique issues in terms of heat management and control, since the detector is both highly heat-sensitive, due to the temperature dependence of the photo-sensitive detector elements, and is also a heat-generator, as a result of the complex system of electronics that is used to convert the output of the individual detector elements into (digital) electrical signals for further processing. To reduce space and minimize noise, these heat-generating electronics are typically close-coupled to the heat-sensitive detector elements within the detector system. The electronics can easily heat up the detector elements, resulting in a loss of image quality.
To deal with this issue, some imaging systems utilize cooling systems to maintain the heat-sensitive detector elements within normal operating temperatures. However, these cooling systems are generally large, complex and costly to implement. For example, U.S. Published Patent Application No. 2005/0117698 to Lacey et al. describes enclosing the detector electronics within a sealed refrigeration unit that includes a solid state heat pump (e.g., thermoelectric cooler) or heat pipe to cool the electronics.
While these large, complex and expensive cooling systems may be suitable for conventional diagnostic imaging systems, which are themselves very large, complicated and expensive devices, such cooling systems are not ideal for smaller and/or lower-cost devices, including mobile devices. There is therefore a need for a compact, low-cost and easily-implemented apparatus for managing temperature in the detector system of an imaging device.